1. Field of the Invention
The present invention relates to a camera with a minimum subject-distance alarm display device.
2. Related Background Art
In a conventional camera with a flash apparatus and a minimum subject-distance (that is, the distance from the camera to a subject or object) alarm display device which can inhibit the flash operation of the flash apparatus by the operation from the exterior of the camera, a range at which an alarm signal representative of the minimum subject distance is generated is equal to not only a range at which a flash exposure is permitted (the flash mode) but also a range at which a flash exposure is inhibited (the flash exposure inhibit mode).
There has been also devised and demonstrated a camera of the type in which, in order to maintain a predetermined depth of focus when the subject distance is close so as to avoid a too deep depth of focus, in case of an exposure at a short subject distance, an aperture limit device is provided so that only when an selected aperture is opened wider than the limited aperture, the aperture is narrowed and a flash exposure is carried out by activating a flash apparatus.
However, in the conventional cameras, "the flash mode" distance is equal to "the flash inhibit mode" distance even though the above-mentioned two distances must be different from each other. As a result, distance at which the minimum subject distance is determined becomes erroneous.
In general, the narrower the aperture, the depth of focus is increased and the degree of resolution of camera lens becomes sharper.
When the quantity of flash light is maintained constant and when it is desired to obtain a most optimum exposure, a flash exposure with a narrower depth of focus than a deep depth of focus must be made when a subject distance is closer. That is, a sharply focused exposure can be attained at a relatively closer subject distance when the flash apparatus is flashed. In the "exposure mode", a flash exposure is possible even when the aperture limit is further made narrower by the flash light and the deep depth of focus can be maintained, but in the case of the "flash inhibit mode" when a subject distance is shorter, the aperture can be widened than the limited aperture and the exposure control can carried out so that the depth of focus becomes shallow. Therefore, a distance at which an exposure is made at a closer subject distance is different.
Furthermore, when the "the flash inhibit mode" is selected, there is a fear that an exposure is carried out against the will of a photographer in the case of a camera whose flash apparatus flashes when an aperture is opened wider than the limited aperture.